This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2002-72669 filed on Mar. 15, 2002, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a structure of installing an injector in a common rail to which fuel for internal combustion engine (hereinafter called xe2x80x9cenginexe2x80x9d) is supplied and a method of the same.
2. Description of Related Art
As shown in FIG. 6, a structure of installing an injector 110 in a common rail 100 in use of a clip and a seal member 111 is well known. The common rail 100 is provided with a delivery pipe 101 extending radially outward. The injector 110 is fixed to the delivery pipe 101. The delivery pipe 101 and the clip 120 are provided on surfaces thereof with protection layers formed by plating or coating for securing erosion resistance and enhancing strength.
For fixing the injector 110 to the delivery pipe 101, the seal member 111 such as an O-ring and the clip 120 are mounted at first on an end portion of the injector 110. Then, the injector 110 is inserted into an interior of the delivery pipe 101. The delivery pipe 101 is provided at an end outer circumference thereof with a pair of projections 102 extending radially outward in opposite directions. The injector 110 is fixed to the delivery pipe 101 in such a manner that the projections 102 are snap engaged with openings 121 formed in the clip 120, while the seal member 111 seals a clearance between an interior wall 101a of the delivery pipe 101 and an outer circumference of the injector 110.
However, when the injector 110 on which the seal member 111 and the clip 120 have been mounted is inserted into the interior of the delivery pipe 101, the projections 102 come in contact with and slide on guide plates 122 for guiding the projections 102 to the openings 121 so that the protection layers formed on the delivery pipe 101 and the clip 120 tend to be peeled off.
If a part of the protection layers is peeled off due to contact between the projections 102 and the guide plates 122, the peeled protection layer falls down or scatters as foreign material 130. As a result, the foreign material 130 is sometimes lodged between the seal member 111 and the interior wall 101a of the delivery pipe 101, which causes the seal member 111 to seal insufficiently. Accordingly, the conventional structure of installing the injector 110 in the delivery pipe 101 has a drawback in that fuel is likely leaked from a joint portion between the injector 110 and the delivery pipe 101.
An object of the present invention is to provide a compact structure of installing an injector in a delivery valve with which foreign material is not lodged between a seal member and an interior wall of the delivery valve.
Another object of the present invention is to provide a simple method of installing an injector in a delivery valve with which foreign material is lodged between a seal member and an interior wall of the delivery valve.
To achieve the above object, in a structure of installing an injector in a common rail for an internal combustion engine, a delivery pipe of the common rail is provided on a surface thereof with a protection layer. A seal member is mounted on the attachment portion of the injector for sealing a clearance between an inner wall of the delivery pipe and an outer circumference of the attachment portion. A clip member has a bottom section mounted on the attachment portion on an opposite side of the seal member with respect to an axial end of the delivery pipe and a resilient sidewall section extending from outer periphery of the bottom section toward the delivery pipe and snap engaged with an outer circumference of the delivery pipe.
With the structure mentioned above, shape of the clip member is formed to satisfy a condition that, when the attachment portion on which the seal member and the clip member have been mounted is inserted into the inner wall of the delivery pipe in a state that the attachment portion is substantially axially aligned with the delivery pipe, the side wall section of the clip member comes in contact with the delivery pipe after the seal member comes in contact with the inner wall of the delivery pipe.
According to the structure mentioned above, foreign material, which is a part of the protection layer peeled off due to contact between the clip member and the delivery pipe, is not lodged between the seal member and the inner wall of the delivery pipe, since, when the clip member comes in contact with the delivery pipe, the seal member has already closely contacted the inner wall of the delivery pipe. Accordingly, the installation structure mentioned above has a superior sealing characteristic.
It is preferable that the delivery pipe is provided at an axial end outer circumference thereof with projections protruding outward and the side wall section of the clip member is provided with openings with which the projections are engaged.
With the projections and the openings, the injector is easily and confidently fixed to the delivery pipe.
A method of installing an injector in a delivery pipe of a common rail for an internal combustion engine with a resilient clip member and a seal member, where the delivery pipe is provided on a surface thereof with a protection layer and at an axial end outer circumference thereof with projections and the clip member is provided with openings, comprises the following steps.
First step is to mount the seal member and the clip member on an outer circumference of the injector so as to position the seal member on a side of an axial end of the injector with respect to the clip member. Second step is to insert the injector into the delivery pipe without causing the clip member to contact with the delivery pipe until the seal member comes in contact with an inner wall of the delivery pipe. Third step is to further insert the injector into the delivery pipe, while keeping a state that the seal member is in contact with the inner wall of the delivery pipe, so that the clip member comes in contact with the delivery pipe. Fourth step is to still further insert the injector into the delivery pipe until the projections are snap engaged with the openings.
The installation method mentioned above has an advantage of preventing the foreign material, which is a part of the protection layer peeled off due to contact between the clip member and the delivery pipe, from being lodged between the seal member and the inner wall of the delivery pipe.